This proposal is to study an aspect of the neural control of breathing in mammals. The long range goal of this laboratory is to explain the genesis and control of respiratory pattern in terms of the biophysical, synaptic and network properties of identified groups of neurons in the central nervous system (CNS). The specific goal of this project is to study pharmacological aspects of synaptic behavior of brainstem respiratory neurons. The interneuronal communications basic to the process of respiratory control by chemical mechanisms and mediated by, as yet unidentified, neurotransmitters. Identification of relevant neurotransmitters, the specific post-synaptic cells on which they act and the importance in understanding respiratory control and pattern generation., The basic premise of this proposal is that local administration of neurotransmitters which affect central respiratory drive, central chemoreceptor or peripheral respiratory afferent inputs, their agonists and/or antagonists will produce measureable, site-specific perturbations in the associated physiological processing. Thus, we propose to look at the effects on respiratory motor outflow and on the activity of individual respiratory neurons produced by perturbations such as alterations in arterial blood gases and/or afferent stimulation before and after ejection of transmitter related drugs in selected regions important in central respiratory control. By analyzing the alterations in respiratory neuronal activity induced by drug application, we will be able to identify the physiological role or the most likely candidates for respiratory related neurotransmitters. Transmitters which are likely to be involved in some manner of respiratory control include glutamate, glycine, GABA, substance P, the catecholamines and enkephalins.